(1) Field of the Invention
The present invention relates to a moisture-permeable waterproof fabric, and a process for the production thereof. More particularly, the present invention relates to a moisture-permeable waterproof fabric having a high moisture permeability and a high waterproofness, and having an excellent abrasion resistance and an excellent washing fastness, and further, to a process for the production of this fabric.
(2) Description of the Related Art
As the conventional process for the production of a processed fabric having a moisture permeability and a waterproofness, for example, a process comprising coating a polyurethane on a fabric and forming cells in the resin layer by wet coagulation is disclosed in Japanese Unexamined Patent Publication No. 58-144178. Furthermore, a process comprising laminating a fabric with a dry-coagulated polyurethane film is disclosed, for example, in Japanese Unexamined Patent Publication No. 58-203172.
Nevertheless, since the moisture permeability and the waterproofness are functions contradictory to each other, according to the above-mentioned conventional techniques using a polyurethane as the material, it is difficult to enhance both properties simultaneously. For example, when the moisture permeability is maintained at 4,000 g/m.sup.2 .multidot.24 hours, it is impossible to obtain a processed fabric having a water pressure resistance higher than 2,000 mmH.sub.2 O.
As the means for overcoming this disadvantage, use of a film formed by wet-coagulating a polyaumino acid-modified urethane is proposed, for example, in Japanese Unexamined Patent Publication No. 60-154054. According to this technique, a processed fabric having a moisture permeability of at least 7,000 g/m.sup.2 .multidot.24 hours and a water pressure resistance of a least 1,500 mmH.sub.2 O is obtained.
Nevertheless, the technique of using a resin layer composed of a polyamino acid-modified urethane is defective in that the abrasion resistance of the resin layer is poor and the washing fastness is extremely low. Namely, the waterproofness and the peel strength are immediately drastically degraded upon washing, and therefore, the processed fabric cannot be put to practical use.
Furthermore, there is known a technique of using a resin layer composed of a mixture of a polyamino acid-modified urethane and a polyurethane, but this technique is defective in that the abrasion resistance and washing fastness are poor. Namely, the waterproofness and peel strength are degraded, and the practical use of this processed fabric is difficult.